Tree and Shrub Expansion Over the Past 34 Years at the Tree-Line Near Abisko,Sweden

Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic Sweden. We recorded the change in coverage of shrub and tree species over a 32– to 34-year period, in three 50 × 50 m plots; in the alpine-tree-line ecotone. The cover of shrubs and trees (<3.5 cm diameter at breast height) were estimated during 2009–2010 and compared with historical documentation from 1976 to 1977. Similarly, all tree stems (≥3.5 cm) were noted and positions determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory.     

Changes in Tree Growth,Biomass and Vegetation Over a 13-Year Period in the Swedish Sub-Arctic

This study was conducted in the Swedish sub-Arctic, near Abisko, in order to assess the direction and scale of possible vegetation changes in the alpine–birch forest ecotone. We have re-surveyed shrub, tree and vegetation data at 549 plots grouped into 61 clusters. The plots were originally surveyed in 1997 and re-surveyed in 2010. Our study is unique for the area as we have quantitatively estimated a 19% increase in tree biomass mainly within the existing birch forest. We also found significant increases in the cover of two vegetation types—“birch forest-heath with mosses” and “meadow with low herbs”, while the cover of snowbed vegetation decreased significantly. The vegetation changes might be caused by climate, herbivory and past human impact but irrespective of the causes, the observed transition of the vegetation will have substantial effects on the mountain ecosystems.     

The dissipation rates of trichlorfon and its degradation product dichlorvos in cabbage and soil

The residual levels and dissipation rate of trichlorfon, and its degradation product, dichlorvos, in cabbage crops and the soil in which these were grown, were determined by gas chromatography at two geographically distant experimental sites, one in Kunming and one in Beijing, China. Trichlorfon was applied at two dosages (900 g ai ha⁻¹ and 1350 g ai ha⁻¹). Maximum final residues of trichlorfon in soil and cabbage were 1.23 mg kg⁻¹ and 1.81 mg kg⁻¹ respectively at Kunming, and 0.35 mg kg⁻¹ and 0.70 mg kg⁻¹ respectively at Beijing. However, the final residues of dichlorvos in both cabbage and soil was only 0.04 mg kg⁻¹ at Kunming, and only 0.03 mg kg⁻¹, or “not detectable”, at Beijing. The mean half-life of trichlorfon in cabbage was 1.80 d with a dissipation rate of 90% over 5 d, while that in soil was 3.05 d with a dissipation rate of 90% over 14 d at one experimental site. The dissipation rates of trichlorfon and its degradation product dichlorvos at the two experimental sites were different, suggesting that degradation of these pesticides was affected by local soil characteristics and climate. When applied at both the recommended dosage and at 1.5 times this, no detectable residues of either trichlorfon or dichlorvos were found in soil or cabbage at harvest. Although trichlorfon can easily degrade into dichlorvos, which is highly toxic to humans and other animals, the observed low residual levels of dichlorvos suggest that trichlorfon is safe when applied at the recommended dosage.     

Biodegradation of nicotine by a novel Strain Shinella sp. HZN1 isolated from activated sludge

The nicotine-degrading bacterium HZN1 was isolated from activated sludge and identified as Shinella sp. based on its physiological characteristics and analysis of 16S rDNA gene. Strain HZN1 is capable of using nicotine as the sole carbon source in the mineral salts medium. The optimum temperature and pH for strain HZN1 growth and nicotine degradation were 30°C and 7.0, respectively. It could degrade approximately 100 % of 0.5 g L(-1) of nicotine within 9 h. Three intermediate metabolites were produced by the strain HZN1 and identified as cotinine, myosmine and nicotyrine using gas chromatography-mass spectrometry. This is the first report of nicotine-degrading strain from the genus of Shinella. The results showed that strain HZN1 could be potentially employed in bioremediation of nicotine. Our findings would provide a new insight into the biodegradation of nicotine.     

Bacterial community composition characterization of a lead-contaminated <Emphasis Type="Italic">Microcoleus</Emphasis> sp. consortium

Introduction  

A Microcoleus sp. consortium, obtained from the Ebro delta microbial mat, was maintained under different conditions including uncontaminated, lead-contaminated, and acidic conditions.     

Phytoremediation of a sulphonated azo dye Green HE4B by <Emphasis Type="Italic">Glandularia pulchella</Emphasis> (Sweet) Tronc. (Moss Verbena)

Purpose  

The dyes and dye stuffs present in effluents released from textile dyeing industries are potentially mutagenic and carcinogenic. Phytoremediation technology can be used for remediating sites contaminated with such textile dyeing effluents. The purpose of the work was to explore the potential of Glandularia pulchella (Sweet) Tronc. to decolorize different textile dyes, textile dyeing effluent, and synthetic mixture of dyes.     

Chitosan membranes as sorbents for trace elements determination in surface waters

Purpose  

Chitosan membranes (non-crosslinked, crosslinked, and modified with l-cysteine) were evaluated as sorbents prior to electrothermal atomic absorption spectrometry (ETAAS) determination of total dissolved metal content in surface water samples.     

Structural isomers of polyfluorinated di- and tri-alkylated phosphate ester surfactants present in industrial blends and in microwave popcorn bags

Introduction  

In this study, we provide strategies for detecting and quantifying the structural isomers of polyfluorinated di- and tri-alkyl surfactants (PFAS) by mass spectrometry (MS). We specifically investigate polyfluorinated dialkylated phosphate ester surfactants (x:2/y:2 diPAPS, (F(CF₂) _x CH₂CH₂O-P(O)(O)⁻-OCH₂CH₂(CF₂) _y F)) and their thioether analogues (x:2/y:2 S-diPAPS, F(CF₂) _x CH₂CH₂SCH₂-C[CH₂O)₂P(O)(O)⁻]-CH₂SCH₂CH₂(CF₂) _y F), which are used for industrial applications, such as oil- and water-repellent coatings on paper and board. DiPAPS have been found in human blood and are metabolised to the persistent perfluoroalkyl carboxylic acids (PFCA) in rats.     

Statistical analysis and isotherm study of uranium biosorption by <Emphasis Type="Italic">Padina</Emphasis> sp. algae biomass

Introduction  

The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass.